The S&P 500 rose 0.75% to 1,872.83 in afternoon trading Tuesday.
The Dow Jones Industrial Average was up 0.67% to 16,355.77, while the Nasdaq was up 1.21% to 4,331.55.
The yield on a 10-year Treasury bond fell 0.78% to 2.68%.
The price of gold slipped 0.95% to $1,359.90 per ounce.
Anaheim drug maker Questcor Pharmaceuticals Inc. rose about 5% to $64.80 for a market value of $3.81 billion. Zacks Investment Research raised its rating on the company's stock from "neutral" to "outperform" last week.
Irvine-based Standard Pacific Corp. was up about 4% to $8.84 for a market value of $3.07 billion.
Newport Beach-based patent licensor Acacia Research Corp. was up about 3% to $16.07 for a market value of $813.78 million.